Several of the hydrocarbon conversion processes used in the refining of petroleum-derived feedstocks involve hydroprocessing, i.e., involve hydrogenation as an essential reaction. Such hydroconversion processes include hydrocracking, reforming, hydrotreating, hydrodealkylation, isomerization and hydroisomerization as well as hydrogenation per se. Except in the case where hydrogenation is essentially the only reaction involved, the hydrogenation catalyst or promoter is combined with another catalyst component which creates the intermediate conversion products which are to be hydrogenated. The components of the overall catalyst composition are thus interrelated in their performance and the net results of the conversion processes dependent upon the peculiar catalytic properties of each component.
In our copending application Ser. No. 417,611, filed Oct. 5, 1989, (incorporated by reference herein in its entirety) there is described and claimed a novel zeolitic catalyst material which, due to its unique activity, selectivity and stability, is found to be highly effective as the acidic constituent of dual function hydrocarbon conversion catalyst compositions. Because of the method by which it is produced, this zeolite catalyst can exhibit various degrees of acidity and thus be readily adapted to convert the desired fraction of hydrocarbon feedstock to lower boiling products. At the same time, its selectivity for the degree of fragmentation of feedstock molecules can be adapted to meet the different requirements of, for instance, mid-barrel hydrocracking and gasoline hydrocracking. In gasoline hydrocracking, multiple fragmentation of the feed molecules is required. In mid-barrel hydrocracking, on the other hand, the average feedstock molecule should be split only once and very near the center of the molecule in order to maximize the mid-barrel fraction, and thereby minimize the production of light hydrocarbons, such as C.sub.1 -C.sub.4 and gasoline.
Another beneficial aspect of this novel zeolite catalyst directly attributable to the method of its preparation is that a significant percentage of its total pore volume (exclusive of inter-crystalline voids) is composed of mesopores, i.e., pores having a diameter of at least 1 nm, preferably in the range of 2 to 60 nm. These large pores are believed to facilitate the conversion of the larger molecular constituents of the hydrocarbon feedstock which cannot enter into the pore system of an as-synthesized zeolite Y.
We have discovered that solid acidic zeolite catalysts constituents such as disclosed in our aforesaid copending application Ser. No. 417,611, when combined with hydrogenation catalyst constituents, are uniquely effective as catalysts in hydroprocessing reactions.